A164683 - OEIS

%I #12 Jun 30 2023 01:09:07

%S 1,8,8,64,64,512,512,4096,4096,32768,32768,262144,262144,2097152,

%T 2097152,16777216,16777216,134217728,134217728,1073741824,1073741824,

%U 8589934592,8589934592,68719476736,68719476736,549755813888

%N a(n) = 8*a(n-2) for n > 2; a(1) = 1, a(2) = 8.

%C Interleaving of A001018 and A001018 without initial term 1.

%C Binomial transform is A083100. Second binomial transform is A164607.

%H Vincenzo Librandi, <a href="/A164683/b164683.txt">Table of n, a(n) for n = 1..300</a>

%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (0, 8).

%F a(n) = 2^(1/4*(6*n-3+3*(-1)^n)).

%F G.f.: x*(1+8*x)/(1-8*x^2).

%t With[{c=8^Range[0,15]},Riffle[c,c]]//Rest (* _Harvey P. Dale_, Aug 08 2017 *)

%o (Magma) [ n le 2 select 7*n-6 else 8*Self(n-2): n in [1..26] ];

%Y Cf. A001018 (powers of 8), A083100, A164607.

%K nonn,easy

%O 1,2

%A _Klaus Brockhaus_, Aug 22 2009